Explosions

What 3 things need to happen for an explosion?

• Fuel

• Oxidation

• Ignition source to set off

What are the basics of improvised explosive devices (IEDs)?

• A critical priority to law enforcement and national security

• Commercially available firearm propellants and fireworks are commonly used as explosive fillers for IEDs

What is the chemistry of primary high explosives?

• Different types of formulations of primary explosives

• Websites or other documentation that describes manufacturing procedure for primary high explosives

What is the chemistry of primary high explosives?

• Different types of formulations of secondary high explosives to include but not be limited to dynamics, TNT, ANFO, etc.

• Methods of manufacture/preparation of secondary explosives

• Use direct physical examination and using a stereoscope to examine

What is TATP?

• Organic peroxide

• 3 peroxide groups

• Cyclical structure

• No nitro group

What is TNT?

• Most used explosive for military, industrial, and mining applications

• Insensitivity to shock and friction, with reduced risk of accidental detonation compared to more sensitive explosives

• 3 nitro groups

• Benzene group

What is ANFO?

Ammonium nitrate/fuel/oil

What is ANFO used for?

• Bulk industrial explosive

• Used in coal and metal mining, quarrying, and civil construction

• Acts as the oxidating agent and absorbent for fuel

What is included in pre-blast analysis?

• Identification of explosives in forensic chem

• Identification of unused explosives is key in counterterrorism and public security

How are explosives traces and detected in the field?

• Checkpoint screening

• Handheld explosive trace detectors

• Portable trace detectors

• TrueTrace

What is CERL?

• Canadian Explosives Research Lab

• The only Canadian government lab that offers explosive testing, analysis, certification, and research related to explosives and their components

What is the explosive database?

• The identification and differentiation of commercial and military explosives via mass spec.

• 36 out of 41 samples of explosives were differentiated

Oklahoma City Bombing

• April 19, 1995 a truck bomb exploded in front of a building

• The bomb was improvised from ammonium nitrate fertilizer, diesel fuel, and nitromethane

• Killed 169 people

London Bombings

• July 7, 2005, 52 people were killed and hundreds injured from coordinated attacks on the transportation system

• Identified the explosive used in the IEDs

• TATP was identified based on finding TATP in the apartment of the biochemist

What were the recovered components when 5 IEDs were consecutively detonated?

• Battery

• Lid of metal can

• Mobile phone

• Printed circuit board

• Metal can

• Handle and

• Combination lock of suitcase

• Push button

What is the general approach to trace explosive investigation?

• Scene

  • Assessment, evidence collection, field analysis

• Lab

  • Examination and analysis

• Report

  • Interpretation

How to collect and preserve evidence?

• Airtight containers

• Do not use plastic bags

• Keep containers separately

• Collect “substrate control” - uncontaminated control sample

What are the standards for explosive-related evidence?

• Terminology

• Intact explosives

• Explosive residue

What are the challenges with post-blast analysis?

• Representative sampling since the amount of sample available may be very small

• Composition changes from one case to another and different matrices can be quite complex

• Non-controlled and heterogeneous phenomenon

• Identification of chemical content and interpretation problems

• Other evidence may be compromised

What were the findings when tracking the explosive source post blast?

• ~30 out of 108 TNT samples recovered

• 0 RDX samples recovered

What method is better for sampling the HME from post-blast IED fragments?

Swab

What were the findings of the study of survival of fingerprints after detonation of IEDs?

• 52 of the 115 deposited FPs were detected, corresponding to a total of FP recovery of ~50%

• Only ~15% of expected DNA recovered

• On avg. loss of DNA from 1 week to 3 months is 98%